Claws, spines, spikes, tentacles, and fangs. Aliens, monsters, and ghostly apparitions glowing in the night. Marine life forms have some of the best looks for Halloween—no costumes needed. From freaky fish lurking beneath the surface to creepy crawlies of the deep, meet some of the sea’s strangest and most haunting characters.

Fangtooth Fish
Credit: © David ShaleThis aptly named fish (Anoplogaster cornuta) has long, menacing fangs, but the adult fish is small, reaching only about 6 inches (17 cm) in length. It's teeth are the largest in the ocean in proportion to body size, and are so long that the fangtooth has an adaptation so that it can close its mouth! Special pouches on the roof of its mouth prevent the teeth from piercing the fish's brain when its mouth is closed.
It has been found as deep as 5,000 meters (16,404 feet), making it one of the deepest living fish, but is most common between 500 and 2,000 meters (1,640 and 6,562 feet). During the day it stays in deeper areas of the ocean and at night, migrates up to shallower water to feed. (This is called a diel migration.) Younger, smaller fangtooth fish filter zooplankton from the water and adults feed on fish and squid.
See more bizarre-looking ocean life in the Creepy Critters Marine Life slideshow and learn more in the Deep Ocean Exploration section. You can see a fangtooth specimen on display in the Sant Ocean Hall at the National Museum of Natural History.

Glowing Sucker Octopus
Credit: © David ShaleThis red octopod (Stauroteuthis syrtensis) shines in a novel way. Suckers stretching in a single row down each arm flash on and off. The glowing-sucker octopod drifts through deep waters off the eastern United States—down to 2,500 meters (8,200 feet)—and grows up to 50 cm (18 inches) long. Learn more about cephalopods and deep ocean exploration on the Ocean Portal.

Blob Sculpin
Credit: NOAA, Alaska Fisheries Science CenterThe ghoulish “blob sculpin” (Psychrolutes phrictus), a deepwater fish found off the Pacific coast of the U.S. from the Bering Sea to Southern California, can grow to about 70 cm (more than two feet) in length and eats small invertebrates. See more bizarre-looking ocean life in a slideshow of the scariest monsters of the deep-sea and learn more about the deep ocean in the Deep Ocean Exploration section.

The Bobbit Worm
Credit: Flickr user JennyHuang
Rhinochimera
Credit: NOAA Okeanos Explorer Program, 2013 Northeast U.S. Canyons ExpeditionWho is that fish coming out of the gloomy dark? A rarely seen Rhinochimera (Harriotta sp.)! Rhinochimera are a type of cartilaginous fish, closely related to sharks and rays. These deep ocean dwellers have big greenish eyes that help them to spot their prey—likely deep-sea invertebrates and fish.

Blackdevil Fish
Credit: E. Widder, ORCA, www.teamorca.orgBlackdevil fish (Melanocetus johnsonii) are quintessential monsters from the deep. The female lurks in the dark, drawing in prey with her glowing lure, while the male attaches to her like a blood-sucking parasite. Females can swallow prey larger than their own bodies.

Zombie Worms Eating Whale Bone
Credit: Yoshihiro Fujiwara/JAMSTECZombie worms (Osedax roseus) eat away at the bones of a dead whale that has fallen to the seafloor in Sagami Bay, Japan. These bizarre worms rely on whale bones for energy and are what scientists call “sexually dimorphic”—the male and female forms are markedly different. In this case, the males are microscopic and live inside the bodies of the female worms! This allows females to produce many, many eggs to disperse across the seafloor. Few of these will land close enough to sunken bones to survive.

The Vampire Squid from Hell
Credit: © 2004 MBARIWith a scientific name that means "the vampire squid from hell," you'd expect the vampire squid (Vampyroteuthis infernalis) to be a fearsome predator terrorizing the deep. Despite its demonic look, that isn't the case; instead, the vampire squid collects and eats drifting particles called "marine snow" using two long, sticky filaments. It doesn't seem like much food to fuel a foot-long cephalopod, but it's enough for it's slow lifestyle in dark, low-oxygen water with few predators.

Black Swallower
Credit:Flickr user Lea Lee

The Toothy Sea Wolf
Credit: Flickr user Kamil Porembiński
Giant Isopod
Credit: Image courtesy of Expedition to the Deep Slope 2006 Exploration, NOAA Vents ProgramThis giant isopod (a crustacean related to shrimps and crabs) was collected from the cold, deep waters of the Gulf of Mexico in 2006. Scientists believe that it is one of about nine species in the genus Bathynomus.

A Shortnose Greeneye Fish Aglow
Credit: Image Courtesy Edie WidderUnder white light, this shortnose greeneye fish (Chlorophthalmus agassizi) looks unimpressive. But, in dim blue light—the type usually seen at depth—it shows its true fluorescent colors.
NOAA scientists collected this specimen during a 2004 expedition for optical studies. The scientists believe the green flourescence of the fish’s eye lenses help it detect prey better in dimly lit water.
Bioluminescent creatures emit and produce their own light, whereas fluorescence is the emission of light by a substance—not always living—that has absorbed light or other radiation of a different wavelength. Animals use bioluminescence for many reasons including communication, but fluorescent creatures depend on the light to determine when they "glow."
According to the scientists who were part of NOAA's 2004 expedition, the shortnose greeneye fish's lens absorbs light that comes from the surface of the ocean, but it lets through the turquoise-colored light of most bioluminescence creatures. This allows the fish to discern the color of its prey in deep ocean waters.

Chimaera from the Deep
Credit: © David ShaleThis rarely-seen smalleyed rabbitfish (Hydrolagus affinis), belonging to the order of Chimaera, was caught during a research trip to the Mid-Atlantic Ridge in 2004 sponsored by the Census of Marine Life. In Greek mythology, chimeras were beasts that were part lion, part snake and part goat, although deep sea Chimaeras are not a combination of animals. Rather, they are related to sharks, but not very closely: the two groups separated evolutionarily around 400 milion yeras ago.

The Goblin Shark
Credit: Dianne Bray / Museum Victoria
Ghost Crab Close Up
Credit: Joseph Poupin, Institut de Recherche de l'Ecole NavalWhat’s that animal popping out of its hole to say boo? A Ghost crab! These ghoulish crabs come out at night to eat their favorite meal…other crabs! The crabs are often seen scuttling quickly along beaches at night, when they emerge from their burrows to feed. They are common in Moorea, an island in the Pacific Ocean, where this specimen was collected.

Venus Fly-Trap Anemone in the Gulf of Mexico
Credit: I. MacDonald (in Gulf of Mexico–Origin, Waters, and Biota. Vol. 1. Biodiversity. Felder, D. L. and Camp, D. K. (eds.) 2009. Texas A&M Press.A venus purse anemone looks like it would fit right in at the Little Shop of Horrors. Resembling the carnivorous Venus flytrap that we are familiar with on land, this anemone is typically in the Gulf of Mexico. Found on the floor of the deep sea, it waits until tiny particles drift onto its tentacles and then fires small stinging harpoons called nematocysts to capture them as food.

Sound the Alarms
Credit: JAMSTECSound the alarm, a monster is headed your way! This monster is a Coronate jellyfish (Atolla wyvillei), sometimes known as an alarm jelly. When a predator is nearby the jelly will release blue light to attract bigger predators to eat or scare their enemy away. Scientists use this technique to get a better look at deep-sea creatures.

Sea Spider
Credit: Scott C. France, Bahamas Deep-Sea Corals 2009 Exploration, NOAA-OERWhat’s that creeping around the ocean floor? A sea spider of course! While most sea spiders (pycnogonids) are small, giant sea spiders can reach almost 3 feet (1 meter) wide! These creepy crawlers eat by sucking nutrients out of their prey using a proboscis.

Howl at the Moon!
Credit: Brad GemmellWhat’s that majestic orb? Not the moon but a moon jelly (Aurelia aurita)! Moon jellies are 95 percent water, but that doesn’t stop them from eating planktonic mollusks, crustaceans, young polychaetes and more.

Skeleton Shrimp
Credit: SINC Agency, Spain & Guerra-García, José ManuelSkeleton shrimp are amphipods (a type of crustacean related to shrimp and crabs). They have grasping legs to hang onto their surroundings as they sway with the current and use their front claws to grab their food—algae, detritus, and copepods. This tiny species only reaches a length of about one-eighth an inch (the female is smaller, only a tenth of an inch, seen here on the left) and is found in a cave off of the California coast on Catalina Island. The species was formally named in 2013 and was named one of the "Top Ten New Species" from that year by the International Institute for Species Exploration.